Spark plug



Jan. 13, 1931. w MCELROY 1,789,078

SPARK PLUG Filed Feb. 2l 1930 INVENTOR,

A TTORNE Y.

Patented Jan. 13, 1931 UNITED STATES wILLIAmncELnoY, or BROOKLYN, nnw'roax SPARK PLUG Application filed February 21, 1930. Serial No. 430,195.

This invention relates to spark plugs for internal combustion engines and is directed more particularly to the construction of the central or insulated electrode of such plugs.

"I The object of the invention is to provide a more efiicient construction for a central electrode, andone so constructed that it will not only keep clean, but will produce a more efficient ignition of combustible fuel within the firingchamber of an associated cylinder.

In practically carrying out the invention, the electrode is provided adjacent the gap with a hollow'chamber preferably filled or substantiallyfilled with relative large granules of carborundum and the wall of the chamber is formed with slots adjacent the gap of the plug. During compression stroke ofthe engine, compressed gases enter into the chamber of the electrode, circulate between the granules of carborundum and be come highly heated and gasified. As soon as a spark occurs at the gap, these gases which because of their heated character flow through the slots are instantly ignited,

so as to facilitate flame propagation within the cylinder. Furthermore the rapid passage of the gases through the slots sets up a scourin' action at the gap which keeps the electro es clean at this point and free from deposits of carbon, oil or other extraneous matter.

Features of the invention, other than those specified, will be apparent from the hereinafter detailed description and claims, when read in conjunction with the accompanying drawings.

7 The accompanying drawing illustrates difierent practical embodiments of the invention, but the constructions therein shown are to be understood as illustrative, only,

and not as defining the limits of the invention.

Figure 1 is a central section of a spark plug embodying the present invention with the central electrode shown in elevation.

Figure'2 is a central section of'the lower end of such electrode. 7

Figure 3 is an underneath plan'view of the same.

d Figure 4 is a side elevation of the election.

tral electrode, and more especially to the i which an ignition lead maybe se'cu-red'bythe L trode showing it in the course of construction.

Figures 5 and 6 are perspective views of asbestos and carb'orundum bodies which may be optionally employed. V Figure 7 is a View similar to Figure 2, but illustrating a modified form of the inven- The plug structure of a plug embodying this invention may begenerally of any con- 00 ventional form. The grounded electrode 1, the shell 2 of the plug and the porcelain 3 may be of any appropriate structure. The

invention is particularly directed to the censpark gap end thereof; The electrode is designated generally by'the reference character l. It embodies a rod, the upperend of which constitutes the binding post to o usual binding nut 5. The lower end of the electrode is made of hollowcylindrical for 'n by providing it with a tubular portion 6.

This tubular portion is provided at its free end with taperingportions 7. Adjacent the base of the tubular portion, the electrode is provlded With a transverse passage 8, and an axial passage 9 connects [a transverse passage withthe interior of the tubular portion. Alined with the passage 9 is a pocket 10 and a rod or wire ll'is adapted to "be seated in the pocket and then looked against withdrawal by laterally offsetting the. .rod in the passage 8 as indicated at"12 in Fig. 2. After the parts have been thus assembled,"

a small quantity of asbestos indicated at 13 is preferably introduced into the base of the tubular portion andthereatter the tubular portion is substantially filled with carborundum granules 14. Thereafter the projec' tions or prongs 7 are-bent inwardlylagainst the rod or wire 11 to thus term within-the lower end of the electrode a substantially closed chamber filled with .carb'orundum granules. V

In the bending in of the prong 7, slots 15 are left atthelower end of the electrode I between the prongs, andthe interior of the chamber is also vented'throug'h the passages ill is wholly omitted.

9 and 8. The asbestos 13 is packed loosely so as to permit of its bending.

lVith this arrangement, it will be apparent that when the plug is in use, motive fuel under compression during the compression stroke of the engine will pass through the slots 15 and through the passages 8 and 9 into the interior of the chamber and fill the interstices between the carborundum granules. This part of the plug will become fairly well heated, so that. the temperature of such gases will be materially raised. Nevertheless the circulation of the gases into the chamber will preclude overheating of the electrode. By the" time ignition takes place, there will be a marked tendency of the heated gases in the chamber to flow out particularly through the slots 15 and as a result, these highly combustible gases will. immediately be ignited by the spark when ignition takes place and there will result not only the spark of the'ignition circuit, but a flame of the said gases and these two combined will greatly expedite flame propagation of the gases of the motive fuel in the cyl nder. Furthermore, by pos1t1on ng the carborundum granulesin the chamber specified, some of the current flowing through theelectrode will be transmitted by way of these granules, which will serve .to greatly intensify the spark; f

In the preferred torm of the invention, ljemploy the rod as stated, but very satisfactory results may be obtained if the rod Furthermore, a short length. of a rivet may beassociated with the apex of thedome at the lower end of the closed chamber, so that a small portion ofthe-rod will extend into, the chamber and a small portion outside the chamber, the :rivet being clamped between the small ends or points ofthe prongs 7. This latter construction has the advantage that the carborundum granules operate with even greater efficiency in intensifying the spark as a greater portion of the current is carried by the granules in the absence of a central c011- ductor l'l as shown.

In the formyof the invention as shown in Fig '2, the carborundum granules are loose with respect to one another. I can "according to this invention,-however, make up these'granules inthe form of a plug 14a as indicated in FigureG by securing the granules together-"by waterglass or some other adhesive' and: the asbestos may also be in the form of: a loose plug 13a as indicatediin Fig; 5. v

iExperience with the plug of the character described has shown it :t0 operate with remarkable efficiency, even in cylinders which were throwing oil. 1

Inthe structure .otIFigur-e, 7;,a lower end of the .electrode s prov ded. with a tubular port1on 6a, hav ng there n, asbestos 13 and .thereof..

her of the electrode. If desired, I may mix with these granules similar granules or pieces of metal such, for example, as nickel oxide. This will decreasethe resistance within the chamber of the electrode and permit a more ready fiow of current theretlirough. 1

The'foregoing description sets forth the invention in its preferred practical form, but the invention is to be understood as fully commensurate with the appendedclaims.

I-laving thus fully described the invention, what I claim as. new and desire to secure by Letters Patent is: Y

1. A spark'plug electrode embodying at .its gap end a'hollow chamber, the walls of which are provided with openings and carborundum granules housed within said chamber. I a

2. A spark plug electrode embodyingeat its sparking end a hollow tubular portion, the free end of which, is provided with prongs bent inwardly to form a slotted closure and to form within said electrode a substantially closed chamber, and carborungum granules positioned within saidchamer. 7 i 1 3. A. spark plug electrode embodyingat its sparking end a hollow tubular. portion, the free end of which. is provided with prongsibent inwardlyto form a slotted closure and to form within said electrode a substantially closed chamber, and carborundum granules positioned within said chamber, and a sparking point extending from the interior of the chamber. to the. exterior lf/A spark plug electrode embodying at its sparkin end a hollow tubular portion, the. free end of which is provided with prongs bent inwardly to form a slotted closure and to form within said electrode a substantially closed chamber, and carborunduni granules positioned within said chamher, said chamber being provided at its base with a passageleading from the intefrior of the chamber to th'ejexterior there 0 5. A spark plug electrode embodyingat its sparking end a hollow tubular portion, the

free end of whichis provided with prongs bent inwardly to form a slotted closureand to form within said electrode a substantially closed chamber, carborundum granules positioned within said chamber, said chamber being provided at its base with a passage leading from the interior of the chamber to the exterior thereof, and asbestos positioned between the carborundum granules and said passage.

6. A spark plug electrode embodying at its gap end a hollow chamber, and carborundum granules housed within said chamber.

7. A spark plug electrode embodying at its gap end a hollow chamber, and carborundum granules and metallic granules housed within said chamber.

8. A spark plug electrode embodying at its gap end a hollow chamber having an open end interiorly threaded, a plug screwed into said hollow end, and having flat sides to provide for passage of gases into and out of said chamber, and granular material positioned within said chamber.

In testimony whereof I have signed the foregoing specification.

WILLIAM MoELROY. 

